In general, an image reading apparatus such as a scanner has a backing at a position facing an image capturing device capturing an image of a document, and switches the position of the backing to change the background color of the document to white color or black color. The image reading apparatus drives the motor to pivot the backing to switch the position of the backing.
For example, an image reading apparatus sets the backing to the initial position with a spring, and drives the motor to move the backing in a direction for compressing the spring, and continues to drive the motor so as to hold the backing at the predetermined position where the spring is most compressed. On the other hand, when the backing is returned back to the initial position, the image reading apparatus cuts off power supply to the motor, and returns the backing from the predetermined position to the initial position with the force of the spring. However, in this case, since it is necessary to continue to drive the motor in order to hold the backing at the predetermined position, the consumed electric power increases.
An optical character reading apparatus configured to correct an output voltage of a CCD image sensor in accordance with a reference level is disclosed. The optical character reading apparatus includes a support mechanism rotatably supporting a white color reference plate into a reading position and a retraction position retracted from this reading position and a cam coming into contact with a roller of the support mechanism, and every time the optical character reading apparatus reads a reading medium, the optical character reading apparatus performs output level correction by rotating the white color reference plate from the retraction position to the reading position. In this optical character reading apparatus, when the cam is rotated, the white color reference plate is rotated and held at the retraction position while the second cam surface is in contact with the roller, and the white color reference plate is rotated to the reading position and held at this reading position while the first cam surface is in contact with the roller (see Japanese Laid-open Patent Publication No. 2002-101266).